1. Field of the Invention
The present invention relates generally to pet foods, and, more particularly, to the preparation of a non-rendered pet food pre-mix product, useful for further processing by a pet food manufacturer. The present invention also relates to a carrier substrate comprising a dried bakery product as a filler in pet food and as an energy-reducing extrusion aid in the processing of pet food.
2. Description of Related Art
The pet food industry has utilized "meat"-based ingredients from its inception. The typical means by which meat is incorporated is in the form of rendered meals, raw meats, meat digests, drum-dried products, and spray-dried products. These meat products are sources from a variety of origins, including, but not limited to, beef, pork, poultry, fish, lamb, venison, horse, and the like that have been determined by the Association of Americal Feed Control Officials (AAFCO) as being of appropriate nutritional quality and functionality in a dry, canned, soft, moist, or treat product (such as biscuits, dry treats, jerky, and moist treats).
The use of meat(s) and their by-products and/or derivatives, has become an essential part of any pet food formulation. In dry pet food, for example, meat meal and poultry meal are widely used to provide palatability and as a source of protein. The advantages of utilizing these rendered products are that they are widely available at a reasonable cost to the manufacturer of the pet food, either dog or cat. In addition, digests which are enzymatically or acid hydrolyzed may be used to enhance the palatability and thus the acceptability to the pet of a given dry or moist pet food. However, as the pet food market has diversified, and through the demand of consumers that manufacturers provide higher quality products for their pets, a need has developed to explore new ingredients that meet nutritional, wholesome, and natural product requirements. Traditionally, meat meal or meat and bone meal and poultry meal or poultry by-product meal are rendered, with the main constituents being that of the offal, which by AAFCO's definition is the "material left behind as a by-product from the preparation of some specific product, less valuable portions, and the by-products of milling".
Thus, in the case of meat and poultry meals or by-product meals, offal would include the viscera, heads, feet, body carcasses, organs, condemned birds (whole chicken and turkey), and blood. The same principal would apply to fish, with the exception of salt, which should not exceed 3% at a maximum of 10% moisture. Fish processing also offers, as do other protein-based ingredients when wet-rendered, a soluble fraction which is obtained by the evaporation of the fish, with the oils part or not part of the soluble fraction which contains soluble protein from the starting material.
Therefore, in order to add, include, or formulate meat-based ingredients, they are typically added in a dry form for ease of handling at the factory level. The use of digests, solubles, or protein hydrolysates are an effective means by which pet acceptability to a product is obtained. However, the extensive uses of the by-products do cause concern to the consumer and have caused manufacturers to look at different ways to include whole meats without the use of the meat's offal in their products.
Typically, this is achieved by the addition of raw or cooked meat to the process, such as by extrusion, whereby the meat is processed under high pressure and temperature and is forced through a restricted orifice, resulting in a cooked gelatinized pet food product. There is much information on the art and technology of extrusion and its practice in both the pet food and food industries, and it is accordingly assumed that the general principals of extrusion are understood by the person skilled in this art.
The addition of raw or cooked meat products (meat, poultry, fish, and the like) to an extrusion system is achieved by pumping a slurry of the meat substrate, either in total or in a combination with other ingredients such as corn syrup, glycerin, propylene glycol, and the like, to complete the desired pet food type (i.e., soft, moist, or dry pet food). The addition of raw meat substrates may create an operational problem with the process due to microbiological concerns, physical space limitations due to plant process designs, and inconsistent pump performance due to viscosity changes, resulting in varied finished product chemistry (i.e., protein, fat, moisture, etc.), and can negatively affect the yield of a dry expanded pet food due to the decreased solids in the formula as a result of the meat addition. The preferred way of incorporating meat substrates to a product is in the dry state or meal form, such as with spray-dried or drum-dried meat products. The problem with directly adding these spray- or drum-dried meats is their cost due to the dehydration methods. Their quality is of good consistency and they are typically added to the surface of the product for palatability enhancement.
Thus, it is desired to provide an effective means by which a pet food manufacturer can add meat substrates to pet food products without having to add raw meat in order to achieve the desired label claim. It is further desired to provide an effective means for adding multiple meat sources at the same time without having to process each meat-based ingredient, with the associated problems described above. Finally, it is desired to offer pet food manufacturers the ability to increase the performance of their extrusion systems.